DE102008022957B4 - Method and device for data transmission - Google Patents

Abstract

A method of data transmission, comprising:
Providing an adaptation value for at least one communication parameter, wherein the adaptation value describes a variation of the at least one communication parameter which is to be enabled during the data transmission, and
Determining the at least one communication parameter before the data transmission such that the variation indicated by the adaptation value is possible during the data transmission without violating a limit value for the at least one communication parameter.

Description

The present invention relates to methods and apparatus for data transmission.

From International Telecommunications Union ITU-T, Telecommunication Standardization Systems and Networks; Digital sections and digital line system - Access networks; Asymmetric digital subscriber line transceivers 2 (ADSL2), pp. 26-33 and table of contents communication parameters are known which are modified during a data transmission.

From the WO 2005/057315 A2 It is known to calculate parameters based on operating data in such a way that a target value for a margin is achieved. This margin describes a transmission power over a minimum required transmission power.

From the US 2006/0080586 A1 it is known to enable a choice of modulation.

The US 2007/0077953 A1 . US 6,704,351 B1 . US 2004/0081233 A1 and US 2007/0064604 A1 describe further methods and devices for data transmission.

The DE 602 03 038 T2 discloses initializing a bit allocation table first and changing it later during transmission.

Thus, it is sometimes desirable to change parameters such as a data transfer rate during transmission. A change in a data rate or other parameter often implies changes in other communication parameters, which may be limited by limits. This can lead to some desired changes not being possible. It is therefore an object to provide ways to ensure that at least some variation of an initial communication parameter is possible during data transmission.

According to embodiments of the invention, methods according to claim 1 or 13 and devices according to claim 22 or 24 are provided. The dependent claims define further embodiments.

The invention will be explained in more detail below with reference to the accompanying drawings with reference to further embodiments. Show it:

1 a schematic diagram of an embodiment of a communication system,

2 a block diagram of another embodiment of a communication system,

3 a flowchart of a method according to an embodiment of the invention,

4 a flowchart of a method according to another embodiment of the invention,

5 a flowchart of a method according to another embodiment of the present invention, and

6 a flowchart of a method according to another embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be explained in detail with reference to the accompanying drawings. The following description is not to be construed as limiting the scope of the invention.

It should be noted that in the embodiments described below, any direct connection or coupling between functional blocks, devices, components, or other physical or functional devices illustrated in the drawings or described herein could also be implemented by indirect connection or coupling. While some of the embodiments are described in the context of DSL (Digital Subscriber Line) technology, it should be understood that the various embodiments are not limited to such communication methods. Rather, the methods and apparatus described below may also be applied to other communication devices and methods, such as wireless communication.

It should also be noted that the features of the various embodiments described herein may be combined with each other unless explicitly stated otherwise.

In 1 a communication system according to an embodiment of the present invention is shown. In the embodiment of the 1 communicates a first communication device 10 via a communication channel 11 with a second communication device 12 , for example by transmission of data over the communication channel 11 , The data transmission over the communication channel 11 may be a bidirectional data transmission, wherein the first communication device 10 and the second Communication device 12 Both are designed as a transceiver, ie as a combined transmitter and receiver, but it can also be a unidirectional data transmission, for example, such that the first communication device 10 as transmitter and the second communication device 12 works as a receiver.

In the communication system according to the embodiment of 1 In the construction of the data transmission, communication parameters are determined in a so-called training phase, including a data transmission rate. In some embodiments, this data transfer rate becomes dependent on characteristics of the communication channel 11 determined, such as depending on noise or other disturbances. In this regard, the communication channel may be a wired communication channel or a wireless communication channel and may include a plurality of sub-channels that may, for example, use different frequency ranges.

Other communication parameters depend on the type of data transmission used, for example DSL data transmission, wireless data transmission or others. In embodiments of the invention, limit values are specified for these communication parameters.

For example, if during communication the properties of the communication channel 11 such as noise or noise, it may be possible to increase the data transmission rate (for example, when noise decreases), or it may be necessary to reduce the data transmission rate (for example, when more interference occurs). In embodiments of the invention, such a change in the data transmission rate is performed without interrupting the data transmission, ie a so-called seamless rate adaptation (SRA) is performed. Changing the data rate often implies changes in other communication parameters, which may be limited by the limit values mentioned above. Therefore, in some embodiments of the invention, the limits may impose limitations on the rate of change of the data transmission rate.

Below, methods according to embodiments which are used, for example, in the communication system of the embodiment of FIG 1 can be implemented to perform the data rate adjustment, taking into account the communication parameters including their limits.

To give a more concrete example of a communication system and the associated communication parameters, reference will now be made to FIG 2 a DSL communication system according to an embodiment of the invention explained. This in 2 illustrated DSL communication system according to an embodiment includes a first DSL modem 20 and a second DSL modem 27 , To simplify the figure is in 2 the first DSL modem as a transmitter of data and the second DSL modem 27 represented as a receiver of data. Of course, the second DSL modem 27 also be designed as a transmitter, and the first DSL modem 20 can be configured as a receiver. In particular, both DSL modems can 20 and 27 be designed as a transceiver.

In one embodiment, the first DSL modem is 20 in an exchange (Central Office, CO), for example an Internet service provider, and the second DSL modem 27 is arranged with a consumer (Customer's Premises, CPE), for example in a private household.

It should be noted that the illustrated elements of the first DSL modem 20 and the second DSL modem 27 are not to be construed as a complete representation of all elements of a DSL modem, and other elements may be provided additionally or alternatively.

The first DSL modem 20 includes an application interface 22 for receiving data, for example, from a computer, another communication system such as a backbone network, and the like. Apart from payload, ie the data to the second DSL modem 27 to be transferred, the application interface is used 22 In addition, control data for controlling the first DSL modem 20 to recieve.

At least the payload is then sent to a forward error correction encoder 23 (FEC encoder), which performs coding to provide forward error correction (FEC). Such encoding may include, for example, a Reed-Solomon coding. In general, forward error correction coding adds redundancy, ie, redundant data to the transmitted data, so that if portions of the data are destroyed during transmission, they can be reconstructed.

The encoded data is then sent to an interleaver 24 forwarded, which performs an interleaving, ie an interleaving. Interleaving generally means that successive pieces of data are spread over a longer period of time be nested and other parts of the data to be sent. As a result, if, for example, a brief glitch destroys or destroys some of the data, it reduces the likelihood that this glitch will destroy a large portion of successive data, which in turn increases the likelihood that the corrupted data will be degraded with the aid of those discussed above Forward error correction can be reconstructed. The interleaver 24 routes the nested data to a transceiver 25 further, which in the in 2 illustrated situation works as a sender. In the illustrated embodiment, the transceiver modulates 25 the interleaved data using discrete multitone modulation (DMT) on a variety of carriers (frequency bands). The data is then in the embodiment of 2 in the form of Asynchronous Transfer Mode (ATM) cells over a communication channel 26 transfer. In other embodiments, other types of modulation may be used.

The first DSL modem 20 further comprises a control circuit or control unit 21 which with the application interface 22 , the FEC encoder 23 , the interleaver 24 and the transceiver 25 communicated. It should be noted that in another embodiment, instead of an internal control unit 21 in the first DSL modem 20 also an external controller (for example, a controller implemented in a computer system) which is the first DSL modem 20 via the application interface 22 controls, may be provided alternatively or additionally.

The second DSL modem 27 includes elements for performing the reverse operations, which of the elements 22 - 25 the first DSL modem 20 were carried out. In particular, the second DSL modem includes 27 a transceiver 28 , which at the in 2 illustrated situation as a receiver for receiving by the transceiver 25 over the communication channel 26 sent data serves. The transceiver 28 performs the appropriate demodulation of the DMT modulated data and passes the demodulated data to a deinterleaver 29 which passes through the interleaver 24 reverses performed nesting of the data, ie outputs the data in the original order. These data are then sent to an FEC decoder 30 which performs forward error correction, that is, that performed by the FEC encoder 23 encoding used to correct errors that may have occurred during the transfer. The decoded data is then sent to an application interface 31 forwarded, which serves the second DSL modem 27 to connect with other devices, such as a computer, other networks and the like and output the data.

The second DSL modem 27 further comprises a control circuit or control unit 32 which with the application interface 31 , the FEC decoder 30 , the deinterleaver 29 and the transceiver 28 communicated.

The control unit 21 and the control unit 32 among other things, control a so-called "handshake", which refers to a section in which the data transmission is initialized or trained. During this handshake, in the embodiment of 2 Communication parameters as already described with reference to 1 mentioned definitely. Such communication parameters include parameters of the DMT modulation, for example a number of bits per symbol, which in turn affects the data transmission rate, the so-called depth of the interleaver 24 and the deinterleaver 29 which determines over which period of time successive data are distributed and which, moreover, one through the interleaver 24 and the deinterleaver 29 caused delay, the size of the FEC encoder 23 used redundancy and the like.

It should be noted that in the embodiment of 2 only a single communication path is shown. In other embodiments, a plurality of parallel communication paths having different latencies may be provided. For example, since, as mentioned above, an interleaver causes a delay, a communication path without an interleaver having a low latency and a communication path with an interleaver which thus has a larger latency but also a greater robustness against glitches may be provided. As already mentioned, limit values can also be provided for the mentioned communication parameters, wherein the limit values can be determined for example in a used communication standard (for example ADSL, ADSL 2, ADSL 2+, VDSL standard, etc.) or can be determined by an operator, for example via the application interfaces 20 and 31.

The following are examples of such parameters for the ADSL 2 standard according to ITU-T G.992.3, as of 12/2006. However, this is to be understood only as an example of the application of embodiments of the present invention and uses similar parameters in embodiments using other communication standards.

According to the ADSL 2 standard, the so-called base frame parameters (base framing parameters) Bp, Mp, Rp, Tp, Dp, Lp, MSGc, SEQp. For these parameters, p is an index indicating the latency path to which the parameter is mapped if, as explained above, a plurality of latency paths are used. Lp defines the number of bits per DMT symbol. For example, this parameter is changed when the data transfer rate is changed during seamless rate adaptation (SRA) or dynamic rate repartitioning (DRR). Dp defines the interleaver depth, such as the depth of the interleaver 24 in 2 , Rp defines the number of Reed-Solomon redundant octets per FEC data frame, an FEC data frame comprising the data over which the FEC coding is performed, for example in the FEC encoder 23 of the 2 , Tp is a ratio of a number of so-called MUX data frames to the number of synchronization octets. In other words, a synchronization octet is inserted with each Tp-th MUX data frame.

Mp defines the number of MUX data frames in an FEC data frame. Bp indicates the nominal number of octets per MUX data frame. If a plurality of so-called frame bearers are assigned to the respective latency path p, Bp is in fact Bp, n and indicates the nominal number of octets of the frame carrier n per MUX data frame. MSGc indicates the number of octets in a message-based portion of a so-called overhead structure, where the overhead structure or overhead bytes generally refer to bytes or data that are not payload but are used to manage the communication. Finally, SEQp refers to the length of the synchronization octet sequence.

If a single latency path is used, so-called service parameters can be calculated as follows, depending on the above basic frame parameters:
The net data rate NDR in bits per second, which is available for the transmission of ATM cells, is calculated as: NDR = 4000 * Lp * Mp * (Bp + (Tp-1) / (Mp * (Bp + 1) + Rp) (1)

The protection against pulse-like noise INP (Impulse Noise Protection) as a number of symbols, essentially the number of consecutive symbols that can be reconstructed by the above-mentioned forward error correction and interleaver technique when they are destroyed, is calculated as: INP = 4 * Rp * Dp / Lp (2)

The delay in milliseconds DELAY is calculated as: DELAY = 2 * (Mp * (Bp + 1) + Rp) * Dp / Lp (3)

The bit rate OR of the overhead channel, ie the logical channel used to transmit the overhead mentioned above, is calculated as: OR = 4000 * Lp * Mp / (Tp * (Mp * (Bp + 1) + Rp)) (4)

The corresponding rate of the message-based portion of the overhead channel MSG is calculated as: MSG = OR * MSGc / SEQp (5)

A corresponding overhead channel period PER in milliseconds is calculated as: PER = 2 * SEQ * Tp * (Mp * (Bp + 1) + Rp) / (Mp * Lp) (6)

Finally, a number of symbols S per FEC frame are calculated according to: S = 8 * (Mp * (Bp + 1) * Rp) / Lp (7) such that an FEC frame (Mp * (Bp + 1) + Rp) comprises bytes.

As can be seen from equations (1) to (7), the parameters thus defined all depend on Lp and thus change as Lp is changed, for example, in a data rate adjustment.

As already mentioned, limit values can be specified for communication parameters. In ADSL standards such as the already mentioned ITU-T G.992.3 standard and also according to ITU-T G.997.1, as of 12/2006, such limit values are specified for the defined service parameters (1) - (7). Since the service parameters depend on the base frame parameters as defined above, this also imposes restrictions on the base frame parameters. In other embodiments, it is also possible to specify limit values for the base frame parameters or for any other communication parameters.

As already general with reference to 1 mentioned, these limits may be set by an operator adjustable or according to the respective standard. In the case of ADSL, a minimum net data rate MinNDR, a maximum net data rate MaxNDR, a minimum protection against pulse-type interference MinINP, a maximum delay MaxDELAY, a minimum data rate of the message-based portion of the overhead Channel MinMSG, and also a minimum reserved data rate net_reserve, which is a minimum data rate always available on demand for a reconfiguration operation, defined by a user or operator as specified in G.997.1.

On the other hand, according to G.992.3, a minimum number of symbols per FEC frame is MinS, a corresponding maximum number MaxS, a minimum overhead channel data rate MinOR, a corresponding maximum data rate MaxOR, a minimum overhead channel period MinPER, and a corresponding maximum period MaxPER defined in the standard.

The user-settable limit values are set, for example, by an Internet service provider and then communicated to the corresponding devices on the customer side during the handshake.

In one embodiment, during the handshake, the communication is set up to maximize the net data rate NDR. If the net data rate is maximized, this may cause other parameters to be near their limits, for example, MSG is only slightly greater than MinMSG, INP is just slightly larger than MinINP, or DELAY is only slightly below MinDELAY. If, during normal operation (also referred to as showtime), the properties, such as the disturbance characteristics, of the communication channel change, as already mentioned, it may be desirable or necessary to change the data rate. In this case, for example, the previously mentioned seamless rate adaptation is used, ie rate adaptation without interrupting the communication, as defined for example in various DSL standards, or a so-called dynamic rate redistribution, wherein a data rate is redistributed between two channels. In this case, the possibilities of data rate adjustment may be limited by the fact that some parameters, such as the MSG, INP or DELAY mentioned above, are already close to their limits and would violate these limits if the data rate is changed. The following are with reference to 3 - 6 Embodiments described which are adapted to such a situation. As will be described in more detail later, these embodiments may be used in combination with each other or independently. In one embodiment, the methods may be as described with reference to FIG 3 - 6 described in the control units 21 and 32 of the 2 be implemented.

In the following, MRAF refers to a maximum (rate) adaptation factor, i. the ratio between the maximum data rate and the minimum data rate. This maximum rate adaptation factor corresponds to a maximum magnification factor MUMF of the data rate if the data rate, for example the data rate at the beginning of the "showtime", corresponds to MinNDR. In other words, by rate matching, this data rate can be increased up to MUMF · MinNDR. On the other hand, MRAF corresponds to a maximum reduction factor MDMF for the data rate when the data rate equals MaxNDR, for example at the beginning of Showtime, so that the data rate can be reduced to MaxNDR / MDMF.

In 3 an embodiment of a communication method via a communication channel is shown, which, for example, in the embodiment of 1 or 2 can be implemented. In step 40 One or more adaptation factors for communication parameters are provided. In other words, in step 40 indicates what factors communication parameters may have to change without violating their limits during communication, eg, when performing a data rate adjustment. In one embodiment, a single factor, such as the factor MRAF given above, is provided and is valid for all parameters. In another embodiment, a single factor is provided which is valid only for selected parameters. In yet another embodiment, individual factors are provided for various parameters, including a factor of 1, which means that the respective parameter need not be able to change. It should be noted that the latter case is the general case, and if all these factors are equal, this corresponds to the case where a single factor is given, and if this single factor is set to MRAF, this corresponds to a case where where a fixed factor is given for all parameters. In another embodiment, a single user-configurable factor may be specified for all parameters, or separate parameters for zooming in and out may be specified. For example, in such an embodiment, MUMF and MDMF, ie, the maximum magnification factor and the maximum reduction factor, may be configurable from 1 to MRAF, either separately for each communication parameter, or globally for all communication parameters.

In embodiments where configurable factors or ranges are specified separately for the various parameters, for example, for ADSL communication parameters, maximum magnification factors for MinINP, MinS, MaxOR and maximum reduction factors for MaxDELAY, MaxS and MinMSG, each factor being between 1 and MRAF in one embodiment. The respective factors are referred to below as MUMF_MinINP, MUMF_MinS, MUMF_MaxOR, MDMF_MaxDELAY, MDMF_MaxS or MDMF_MinMSG. Of course, the same principle can also be applied to other communication parameters.

The at least one adaptation factor of the step 40 may be permanently stored in a memory of the communication system and / or provided by a user and transmitted from one communication device to another communication device, e.g. 1 from the first communication device 10 to the second communication device 12 or in 2 from the first modem 20 to the second modem 27 , This transmission corresponds to the notification of a so-called "service policy", ie a definition for a respective service.

In step 41 a training of the communication channel is performed, which includes a determination of the relevant communication parameters as exemplified above. During this workout, the one in step 40 provided at least one adaptation factor considered. In other words, for example, while the net data rate NDR is maximized as much as possible within the limits for this net data rate, the remaining communication parameters are determined such that they can later be changed by the at least one adaptation factor without violating their limits.

In step 42 the so-called Showtime, ie the transmission of user data, is started. As indicated by dashed arrows, at any time during Showtime in step 43 a data rate adjustment is performed, since, in the training of the communication channel of the in step 40 provided at least one adaptation factor, the data rate adjustment with the associated change of various communication parameters is possible without violating the limits of the communication parameters.

In 4 another embodiment is shown. In the embodiment of 4 be in step 45 provided limit violations for communication parameters. In other words, in step 45 Determines which communication parameters may exceed their respective limits during Showtime, and possibly how far they are allowed to exceed their limits. This can be realized, for example, by providing additional limits which are valid during showtime and which are below the minimum values of the limits discussed above or above the maximum values of the limits discussed above. For example, a minimum value MinINPshowtime may be provided for INP, a new value MaxDELAYshowtime for DELAY, values MinMSGshowtime, MinSshowtime, MaxSshowtime, MaxORshowtime, and the like. Instead of providing such new thresholds, which are valid during showtime, equally allowed threshold variation relative to the thresholds discussed above, such as MinINP, MinS, etc., may be provided.

In this embodiment, separate limit violations may be allowed for each parameter. In one embodiment, the limit violations may have a specific value indicating that any limit violation is allowed, i. during showtime no limit exists anymore.

It should be noted that, for example, by setting the limit during Showtime, which is in step 45 is set to the original value (for example, by setting MinINPshowtime to MinINP), for certain parameters no limit violation can be allowed. Therefore, in one embodiment, limit violations, either predetermined limit violations or any limit violations, may be allowed for only some of the parameters. In another embodiment, any threshold violation may be allowed for each parameter.

In step 46 the training of the communication channel is performed, which in this embodiment substantially corresponds to the conventional training, with only the original limits known. In step 47 the data transmission, ie the Showtime, is started. If at any time during Showtime in step 48 a data rate adjustment is performed, during the data rate adjustment, the initial limits of the communication parameters may be as determined by step 45 be violated.

Similar to the embodiment of 3 the provision of the permitted limit violations may be understood as notification of a new service policy, and similar to the adaptation factors of the embodiment of FIG 3 For example, the limit violations may be permanently stored in memory, configurable by an operator, or both, and may be of one type Communication device to be communicated to another communication device.

In the embodiment of 4 become the allowed limit violations during the training of the communication channel in step 46 not taken into account, but only during the data rate adjustment of step 48 used. Therefore, it is not necessary step 45 before the training of the communication channel, but this step can be performed at any time before the data rate adjustment. This is exemplified in the embodiment of FIG 5 which shows a modification of the embodiment of FIG 4 is.

In the embodiment of 5 will be in step 50 the training of the communication channel as in step 46 from 4 performed and in step 51 will the data transfer, ie Showtime, as in step 47 from 4 started. At some point during the showtime will be in step 52 allowed limit violations provided, with step 52 apart from his position during the showtime step 45 from 4 equivalent. In step 43 becomes a data rate adjustment according to step 48 from 4 in which communication parameters can be changed and their limits according to the allowed limit violations, which in step 52 were injured.

It should be noted that in other embodiments, the step of providing the allowable limit violations may also be performed more than once. For example, allowed limit violations may occur during start-up of the communication system as in step 45 in 4 and later during Showtime, the allowed limit violations can be made one or more times as in step 52 from 5 be changed.

In the case of the embodiment of 5 in which the allowed limit violations are provided during showtime, an overhead channel may be used to communicate the allowed limit violations via a corresponding message in the overhead channel.

In 6 is shown a further embodiment of a method for data transmission. A step 55 This procedure can be similar to steps 45 and 52 of the 4 respectively. 5 be done either before or after the start of Showtime. In step 55 a change in the depth of an interleaver is allowed. In the above example of ADSL communication, this corresponds to allowing a variation of the parameter Dp. step 55 in turn corresponds to the notification of a new service policy.

Later, when data rate adjustment is performed during Showtime, the interleaver depth is changed in this embodiment. In DSL communication systems, as already mentioned, the data rate adaptation is essentially carried out by changing the number of bits per symbol, ie the parameter Lp. In one embodiment, the interleaver depth is changed such that the ratio Dp / Lp is kept approximately constant, for example, kept constant within ± 10%. In the example of ADSL, the parameters INP and DELAY depend on this ratio Dp / Lp. Therefore, if a data rate adjustment with a corresponding connection of the interleaver depth in step 56 Also, the parameters INP and DELAY are kept approximately constant, which reduces the risk of violation of limits by these parameters.

As already mentioned, the embodiments of the 3 - 6 be combined in different ways. For example, if the embodiment of 6 with the embodiment of 3 or the embodiment of 4 no or only small adaptation factors or threshold violations are provided for communication parameters which are kept approximately constant by changing the interleaver depth when performing the data rate adjustment, such as INP and DELAY in the case of ADSL communication.

If the embodiment of 3 with the embodiment of 4 or 5 For some parameters, adaptation factors can be provided, while for other parameters, limit violations are allowed. In one embodiment, for example, no limit violations are allowed for limit values, which may not be violated for technical reasons. For example, for ADSL 2+ systems MinS is 1/3 and must not be violated to prevent a so-called "transmitter stucco". For such parameters whose limits may not be violated for technical reasons, adaptation factors can be provided in one embodiment.

It should be noted that, for bidirectional data transmission, the above embodiments may be used separately for the two directions of communication, for example, in the upstream direction and the downstream direction. In other words, different adaptation factors and / or permitted limit violations for the two different communication directions are provided, and / or a change in the interleaver depth as in the embodiment of FIG 6 can be allowed for only one direction, for both directions or for no direction.

Next, some configuration examples will be given using ADSL as an example. It should be noted, however, that as already mentioned similar communication parameters are also present in other communication standards, for example in other DSL standards or wireless standards, and the embodiments of the 3 - 6 can also be applied to such other standards.

For example, in one embodiment of an ADSL system like the one in FIG 2 shown a combination of the embodiment of 3 with the embodiment of 3 with the embodiment of 4 or 5 used.

In this case, in one embodiment, violation of the upper limits for the data rate of the overhead channel OR and the number of symbols per FEC frame, ie for the parameters MaxOR and MaxS, is allowed. Therefore, it is communicated that these limits may be violated. For MinS, no limit violation is allowed in this embodiment, and an adaptation factor as in step 40 from 3 is provided, which in this case, since MinS is a lower limit, is a maximum magnification factor. In one embodiment, this factor MUMF_MinS is set to MaxNDR / MinNDR, ie to MRAF. In another embodiment, if a corresponding factor for MinINP is less than this value, MUMF_MinS is set to MUMF_MinINP.

In this embodiment, if MinINP equals zero, this limit need not be taken into account because INP is always greater than or equal to zero. On the other hand, if MinINP is greater than zero, MUMF_MinINP is set to (1 + MRAF) / 2 in one embodiment. It should be noted that a larger value of MUMF_MinINP gives more latitude for later data rate adjustment, but makes it harder to reach showtime, i. to find a configuration during training that meets the requirements. On the other hand, a lower value for MinINP gives less latitude for data rate adjustments and therefore, if e.g. Disruptions decrease, the possible increase in performance smaller.

In one embodiment, MinMSG is set to 4000 and MDMF_MinMSG is set to MaxNDR / MinNDR, so that the full range is possible with respect to this limit.

If there is no interleaving (which is indicated by MaxDELAY = 1 in ADSL), MaxDELAY may be violated by data rate adjustment in one embodiment, since in this case, data rate reduction only increases the transmission delay, which is acceptable. If MaxDELAY> 1, interleaving is present. In this case, according to one embodiment, a violation of MaxDELAY is acceptable. According to another embodiment, an adaptation factor MDMF_MaxDELAY = MaxNDR / MinNDR is selected.

It should be noted that the values given above serve only as examples, and in other embodiments other values may be chosen.

In another embodiment, in addition to the embodiments of the 3 and 4 or 5 the embodiment of 6 used, ie a change in the interleaver depth is allowed. In this case, in one embodiment, the same values as above are used, with the exception of MinINP and MaxDELAY. As already explained, by changing the interleaver depth, as the data rate is adjusted, INP and DELAY remain approximately constant. Minor changes in these values may be caused, for example, by a granularity of Dp, or in other words, the possible interleaver depths provided by the interleaver being used. In one embodiment, in this case, an adaptation factor slightly greater than 1 may be provided for MinINP and MaxDELAY, for example MUMF_MinINP = 1.1 and MDMF_MaxDELAY = 1.1.

Referring again to the embodiment of 3 is, as already explained, the at least one adaptation factor, which in step 40 is provided during the training of the communication channel in step 41 considered. In one embodiment, this is done by using limits during training that correspond to the actual limits multiplied by the particular adaptation factor. For example, if MinINP has a MUMF of 1.5 and the limit is MinINP = 2, training is done with MinINP = 1.5 · 2 = 3.

In other embodiments, dependencies between the parameters are taken into account. For example, when ADSL is used as an example, it can be seen from Equation (2) that INP decreases as Lp increases. If during trainning as NDR the maximum net data rate MaxNDR is reached, during later data rate adjustments the data rate is only reduced or, in other words, Lp is decreased, increasing INP. In such a case, in the above example, MinINP may also be set during training as MinINP = 2, since there will be no reduction in INP due to data rate adjustments.

In this regard, in one embodiment, again using ADSL as an example, a permutation is made over all allowed values of the base frame parameters, and those parameters are selected for data transmission in which the NDR is maximized and all service parameters are within their limits. In one embodiment, this is accomplished by first checking for the permutation with the largest NDR (if smaller than MaxNDR), whether the service parameters are within their limits, then for the next largest NDR, etc., until a configuration is found where all service parameters are within their limits.

In one embodiment, where MinINP, MinS, MaxOR, MinMSG, MaxDELAY and MaxS adaptation factors are specified, the following checks are made to determine if the service parameters are within their limits, taking into account the adaptation factors. In the following, ">=" means "greater than or equal to" and "<=""less than or equal to".

μ1 / NDR> = MinINP if NDR> = MaxNDR
μ1 / NDR> = MinINP * MUMF_MinINP if NDR <= MaxNDR / MUMF_MinINP
μ1 / NDR> = MinINP * MaxNDR / NDR if MaxNDR / MUMF_MinINP <NDR <MaxNDR
where μ1 = 4 * Dp * Rp * 4000Mp * (Bp + (Tp-1) / Tp) / (Mp * (Bp + 1) + Rp) so that INP = μ1 / NDR and MUMF_MinINP> 1.

In other words, if NDR> = MaxNDR, INP is greater than or equal to MinINP, if NDR <= MaxNDR / MUMF_MinINP, then INP must be greater than or equal to MinINP · MUMF_MinINP and if MaxNDR / MUMF_MinINP <NDR <MaxNDR, INP must be greater than or equal to MinINP · MaxNDR / NDR, so that the respective parameter set meets the requirements regarding INP according to this embodiment. If MUMF_MinINP = 1 it only needs to be checked if INP> = MinINP, as in this case no reserve for later changes is required.

μ2 / NDR> = MinS if NDR> = MaxNDR
μ2 / NDR> = MinS * MUMF_MinS if NDR <= MaxNDR / MUMF_MinS
μ2 / NDR> = MinS * MaxNDR / NDR if MaxNDR / MUMF_MinS <NDR <MaxNDR
where μ2 = 32000 * Mp * (Bp + (Tp-1) / Tp) so that S = μ2 / NDR and
MUMF_MinS> 1 (if MUMF_MinS = 1 only S> = MinS must be checked).

NDR / μ3 <= MaxOR if NDR> = MaxNDR
NDR / μ3 <= MaxOR / MUMF_MaxOR if NDR <= MaxNDR / MUMF_MaxOR
NDR / μ3 <= MaxOR * NDR / MaxNDR if MaxNDR / MUMF_MaxOR <NDR <MaxNDR,
where μ3 = Bp * Tp + Tp-1 such that OR = NDR / μ3 and MUMF_MaxOR> 1 (if MUMF_MaxOR = 1, only OR <= MaxOR must be checked).

μ4 * NDR> = MinMSG if NDR <= MinNDR
μ4 * NDR> = MinMSG * NDR / MinBDR if NDR <= MinNDR * MDMF_MinMSG
μ4 * NDR> = MinMSG * MDMF_MinMSG if
MinNDR * * MDMF_MinNDR MDMF_MinMSG <NDR <MaxNDR
where μ4 = MSGc / SEQ / (Tp * (Bp + 1) -1) so that MSG = μ4 * NDR and
MDMF_MinMSG <1 (if MDMF_MinMSG = 1, only MSG> MinMSG needs to be checked).

μ5 / NDR <= MaxDELAY if NDR <= MinNDR
μ5 / NDR <= MaxDELAY * NDR / MinNDR if NDR <= MinNDR * MDMF_MaxDELAY
μ5 / NDR <= MaxDELAY * MDMF_MaxDELAY if
MinNDR * MDMF_MaxDELAY <NDR <MaxNDR
where μ5 = 8000 * Dp * Mp * (Bp + (Tp-1) / Tp) so that DELAY = μ5 / NDR and
MDMF_MaxDELAY> 1 (if MDMF_MaxDELAY = 1 only DELAY <= MaxDELAY checked).

μ6 / NDR <= MaxS if NDR <= MinNDR
μ6 / NDR <= MaxS * NDR / MinNDR if NDR <= MinNDR * MDMF_MaxS
μ6 / NDR <= MaxS * MDMF_MaxS if MinNDR * MDMF_MaxS <NDR> MaxNDR
where μ6 = 32000 * Mp * (Bp + (Tp-1) / Tp) = μ2 so that S = μ6 / NDR and
MDMF_MaxS> 1 (if MDMF_MaxS = 1, only S <= MaxS has to be checked).

The first checks for MinINP are the same as above, but the actual limit for INP to be considered during training depends on the received NDR. Similar considerations apply to the usual parameters.

Again, it should be emphasized that the above examples merely serve to illustrate an example implementation in an ADSL system, and other implementations are possible with both ADSL systems and other standards-based systems.

As already mentioned, the provision of rate adaptation factors, allowed limit violations, and / or permitting a change in the interleaver depth in the above-mentioned embodiments may be regarded as notifying a new service policy. In one embodiment, this service policy is communicated by use of one or more users. These parameters may include a parameter already used for other purposes in a communication standard and / or a parameter introduced to communicate such a service policy. For example, in one embodiment, which in turn relates to ADSL, the service policy parameter CIPOLICY, which was introduced in the G.992.3 standard with the third amendment (Amendment 3), can be extended. In the currently standardized form, this parameter may select between a service policy that attempts to maximize NDR and a service policy that attempts to maximize INP for maximum protection against bursty interference. This parameter exists for both the upstream and downstream directions, ie separately for the two directions of bidirectional communication.

In one embodiment, this parameter will expand to a 6-bit parameter, with the most significant bit used to indicate that an additional service policy such as that described above must be considered for reconfiguration, ie, rate adaptation or rate redistribution, and that further parameters which describe how to implement this. In other words, after this parameter in this embodiment, further parameters follow, which in one embodiment may be all 6-bit parameters. The first following 6-bit parameter indicates which aspects are to be implemented. For example, a value of 1 for this first parameter, which may be referred to as reconfig_policy, may indicate that the combination of the embodiment of FIG 3 with the embodiment of 4 and 5 to use, and a value of 2 indicates that in addition the embodiment of 6 should be used. Other values may indicate other aspects, such as using one of the embodiments alone. Then, in one embodiment, the following 6-bit parameters follow:

MUMF_MinINP
MUMF_MinS
MUMF_MaxOR
MDMF_MinMSG
MDMF_MaxDELAY
MDMF_MaxS
MinINPshowtime
MinSshowtime
MaxORshowtime
MinMSGshowtime
MaxDELAYshowtime
MaxSshowtime

This selection of parameters relates to the example given above, in which it was explained in detail for which service parameters adaptation factors are specified and for which other parameters limit value violations are permitted. In other embodiments, the choice for which parameters provide adaptation factors and for which parameters limit violations are allowed may be different, and accordingly the parameters used may be different.

The MUMF or MDMF values may be encoded as (MUMF (or MDMF) -1) /0.125 to give a valid range of 1-56, where 0 and 63 are special values, where 0 is no reserve (ie a factor 1) and 63 means the full reserve MaxNDR / MinNDR. In this embodiment, MinINPshowtime becomes like the corresponding limit MinINP with a special value 63 which indicates no limit and a special value 0 which means that during showtime the same value, i. MinINP, while training is valid or in other words no limit violation is allowed, coded. These two special values 63 and 0 in the presently discussed embodiment also apply to the other parameters indicative of allowable limit violations, i. the above parameters, which end with "showtime".

MinSshowtime can be encoded by using the reciprocal of the minimum value actually allowed during Showtime.

MaxORshowtime can be coded by subtracting 64 from the maximum allowed value in Kbits / s. MinMSGshowtime can be encoded by specifying the minimum allowed value in Kbits / s.

MaxDELAYshowtime can be coded by specifying the delay in ms. Finally, MaxSshowtime can be encoded by dividing the maximum allowed value for S by Mp minus 32.

Of course, these encodings and parameters are meant to be exemplary only of how an embodiment of the present invention could be implemented, and other encodings and parameter systems may also be used to communicate the necessary information. For example, in other embodiments, the Parameter have a number of bits other than 6.

In one embodiment, the mentioned 6-bit parameter reconfig_policy is subdivided, with the three least significant bits having the meaning explained above, that is, indicating which aspects to use. The three most significant bits in this embodiment may be called reconfig_policy_preselect and indicate whether further parameters like those given above or predetermined stored values should be used for these parameters. For example, reconfig_policy_preselect = 0 may indicate that parameters are following, and a value other than 0 indicates the number of a parameter set to be used. It is also possible to save only a single parameter set, in which case a value of reconfig_policy_preselect not equal to 0 may indicate that the stored set is to be used. According to the examples given above, for example, the following parameter sets can be stored: reconfig_policy_preselect = 1 (9) MUMF_MinINP = 4
MUMF_MinS = 63
MUMF_MaxOR = 0
MDMF_MinMSG = 63
MDMF_MaxDELAY = 0
MDMF_MaxS = 0
MinINPshowtime = 0
MinSshowtime = 0
MaxORshowtime = 63
MinMSGshowtime = 0
MaxDELAYshowtime = 63
MaxSshowtime = 63 reconfig_policy_preselect = 2 (10) MUMF_MinINP = 4
MUMF_MinS = 63
MUMF_MaxOR = 0
MDMF_MinMSG = 63
MDMF_MaxDELAY = 63
MDMF_MaxS = 0
MinINPshowtime = 0
MinSshowtime = 0
MaxORshowtime = 63
MinMSGshowtime = 0
MaxDELAYshowtime = 0
MaxSshowtime = 63 reconfig_policy_preselect = 3 (11) MUMF_MinINP = 0
MUMF_MinS = 63
MUMF_MaxOR = 0
MDMF_MinMSG = 63
MDMF_MaxDELAY = 0
MDMF_MaxS = 0
MinINPshowtime = 0
MinSshowtime = 0
MaxORshowtime = 63
MinMSGshowtime = 0
MaxDELAYshowtime = 63
MaxSshowtime = 63 reconfig_policy_preselect = 4 (12) MUMF_MinINP = 0
MUMF_MinS = 63
MUMF_MaxOR = 0
MDMF_MinMSG = 63
MDMF_MaxDELAY = 0
MDMF_MaxS = 0
MinINPshowtime = 63
MinSshowtime = 0
MaxORshowtime = 63
MinMSGshowtime = 0
MaxDELAYshowtime = 63
MaxSshowtime = 63

Parameter sets (9), (10) and (11) are intended for a service policy which uses adaptation factors and limit violations, that is to say exemplary embodiments 3 . 4 and 5 but no change in interleaver depth as in the embodiment of FIG 6 , The parameter set (12) additionally uses the exemplary embodiment of FIG 6 ,

The parameter set (9) is adapted to a communication situation in which MinINP> 0 and which is not sensitive to delay, that is, in which a higher delay can be tolerated. Therefore, MaxDELAYshowtime is set to 63, which means that this parameter may be violated. The parameter set (10) corresponds to a communication situation in which MinINP> 0 and which is delay-sensitive. In this case, no limit violation is allowed for MaxDELAY, and instead an adaptation factor is set for MaxDELAY, which corresponds to the full range.

The parameter set (11) refers to a situation where MinINP = 0.

As already mentioned, parameter set (12) is intended to be used when a variation of the interleaver depth as in the embodiment of FIG 6 allowed is. In this case, injuries from MinINP and MaxDELAY can be accepted as these injuries generally remain small as Dp / Lp is kept approximately constant.

Depending on the communication situation, other predefined parameter sets can also be stored. Furthermore, if communication standards other than ADSL are used, other sets of parameters can be stored accordingly.

The above embodiments are merely exemplary. While embodiments have been explained with reference to ADSL as defined in the corresponding standard, other standards and corresponding other communication parameters may be used in other embodiments. Further, while in the above embodiments limit violations and adaptation factors related to service parameters depending on basic frame parameters according to equations (1) - (7) are provided, in other embodiments limit values, adaptation factors, and / or limit violation allowances may be specified directly for the base frame parameters.

Furthermore, while in the above embodiments adaptation factors are indicated, in other embodiments, instead of a factor, an adjustment value may be indicated which indicates an area in which the respective parameter can move. For example, instead of specifying a MUMF of 1.5 for MinINP and setting a value of MinINP to 2 as the limit, it may also be possible to indicate that the INP value should be between 2 and 3. Similarly, as already mentioned, the limit violations may be specified as new limits during showtime, as reserves by which the limits may be violated, or as multiplicative factors.

Claims (25)

A method of data transmission, comprising: Providing an adaptation value for at least one communication parameter, wherein the adaptation value describes a variation of the at least one communication parameter which is to be enabled during the data transmission, and Determining the at least one communication parameter before the data transmission such that the variation indicated by the adaptation value is possible during the data transmission without violating a limit value for the at least one communication parameter. The method of claim 1, wherein the at least one communication parameter comprises a plurality of communication parameters, and wherein the providing comprises providing an individual adaptation value for each of the plurality of communication parameters. The method of claim 1 or 2, wherein the adaptation value comprises an adaptation factor which indicates a relative variation with respect to the limit value. Method according to one of claims 1-3, wherein the determining of the at least one communication parameter during a training phase for the data transmission is performed. Method according to one of claims 1-4, wherein the at least one communication parameter is determined in dependence on a further limit value which is determined as a function of the adaptation value and the limit value. The method of any one of claims 1-5, wherein determining the at least one communication parameter comprises: Determining if the limit can be violated during data transmission, and Disregarding the adaptation value if the limit value can not be violated during the data transmission. The method of any of claims 1-6, further comprising: Performing a data rate change during the data transmission, wherein the data rate variation comprises varying the at least one communication parameter. The method of claim 7, wherein the data rate change comprises a seamless rate adjustment and / or a dynamic rate reallocation. Method according to claim 7 or 8, comprising: varying a depth of an interleaver used in the data transmission ( 24 ) when performing the data rate change. Method according to claim 9, wherein the depth of the interleaver ( 24 ) is changed so that a ratio of a parameter indicating a number of bits per symbol of the data transmission to the depth is kept approximately constant. The method of any one of claims 1-10, further comprising: Providing a threshold violation parameter for at least one further communication parameter, the threshold violation parameter indicating an allowed threshold violation for an additional threshold of the at least one further communication parameter. Method according to one of the preceding claims, wherein the data transmission is a DSL data transmission. A method of data transmission, comprising: Providing a threshold violation parameter for at least one communication parameter of the data transmission, wherein the at least one communication parameter is determined prior to the data transmission in compliance with the threshold, the threshold violation parameter describing an allowed violation of a threshold of the at least one communications parameter during data transmission. The method of claim 13, wherein the threshold violation parameter replaces the threshold during transmission of payload data. The method of claim 13 or 14, further comprising: varying a depth of an interleaver ( 24 ) which is used in data transmission when a change in the data transmission rate is performed. The method of any of claims 13-15, wherein the data transmission is a DSL data transmission. The method of any one of claims 13-16, wherein the at least one communication parameter comprises a plurality of communication parameters and individual limit violation parameters are specified for each communication parameter. A method of data transmission, comprising: Communicating a service policy, wherein the service policy comprises at least one indication selected from the group consisting of: an indication that at least one adaptation value for a communication parameter of the data transmission is to be provided for a method according to one of Claims 1-12 and an indication that at least one limit violation parameter is to be provided for a communication parameter of the data transmission for a method according to one of Claims 13-17. The method of claim 18, wherein the service policy further comprises the at least one adaptation value and / or the at least one limit violation parameter. The method of claim 18, wherein the service policy further comprises an indication of a stored set of adaptation values and limit violation parameters. The method of any one of claims 18-20, wherein the data transmission is an ADSL data transmission. Contraption ( 10 . 12 ; 20 . 27 ) for data transmission, comprising: a communication circuit ( 22 - 25 . 28 - 31 ) for data transmission via a communication channel ( 11 ; 26 ) according to at least one communication parameter, a control circuit ( 21 . 32 ) connected to the communication circuit ( 22 - 25 . 28 - 31 ) in order to determine the at least one communication parameter before the data transmission such that a variation of the at least one communication parameter indicated by a provided adaptation value during the data transmission is possible without violating a predetermined limit value for the at least one communication parameter, wherein the adaptation value describes a variation of the at least one communication parameter which is to be enabled during the data transmission. Apparatus according to claim 22, wherein the apparatus is adapted to carry out the method according to any one of claims 1-12. Contraption ( 10 . 12 ; 20 . 27 ) for data transmission, comprising: a communication circuit ( 22 - 25 . 28 - 31 ) for communicating via a communication channel ( 11 ; 26 ) according to at least one communication parameter, one with the communication circuit ( 22 - 25 . 28 - 31 ) coupled control circuit ( 21 . 32 ) to vary the at least one communication parameter, wherein a limit violation parameter for the at least one communication parameter describes an allowed violation of a threshold of the at least one communication parameter during data transmission, wherein the control circuit is adapted to supply the at least one communication parameter prior to the data transmission in compliance with the limit determine. Apparatus according to claim 24, wherein the apparatus is adapted to carry out the method according to any one of claims 13-17.

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